1. Field of the Invention
The present invention generally relates to a latch device, and more particularly to a push-push latch that has a lever arm rotatively coupled to a latch body. The push-push latch may open or close in response to a force applied to the lever arm of touch latch.
2. Description of the Related Art
A latch may be used to secure one moveable surface relative to another surface. One type of latch is a touch latch, which may also be known as a push-push latch. When an arm of a touch latch is in an open position, pushing the arm of the touch latch may cause the touch latch to move to a closed position. When the arm is pushed again, the arm of the touch latch may move back to the open position. Touch latches may be used as component parts in systems that latch doors, cabinets, drawers, windows, and the like.
A touch latch may have a path formed in a body of the latch. The path may be formed as a groove within the body of the latch. A locking member of the touch latch may be attached to an arm. The arm typically is coupled to a tracing member that follows the path in the latch body. The path typically has two stable points. When the tracing member is located at the first stable point, the touch latch is in an open position. When the tracing member is located at the second stable point, the touch latch is in a closed position. A spring may be positioned within the body to bias the arm away from the body. The spring may force the tracing member to move to one of the two stable points in the path during operation of the touch latch.
In one type of touch latch, the arm is rotationally attached to the body of the touch latch. U.S. Pat. No. 4,215,884, issued to Little, which is incorporated by reference as if fully set forth herein, describes a rotational type of touch latch. The touch latch has an xe2x80x9cLxe2x80x9d shaped arm. A first leg of the xe2x80x9cLxe2x80x9d shaped arm traces a path within the body of the touch latch. The second leg of the xe2x80x9cLxe2x80x9d shaped arm may be contacted by a closure member. When the touch latch is in the open position, pushing the second leg with the closure member rotates the second leg towards the body and causes the first leg to move along the path from the first position to the second position. Pushing the second leg towards the body a second time causes the first leg to move from the second position to the first position and rotates the second leg away from the body of the touch latch. The body of the touch latch may have to be large to accommodate the range of motion of the first leg within the body of the touch latch. Many currently available small, rotational arm touch latches have maximum force ratings of approximately 3 pounds. It is desirable to have a small touch latch that is able to withstand greater than 50 lbs. of force.
In another type of touch latch, an arm of the latch retracts into a body of the latch when the arm moves from an open position to a closed position. U.S. Pat. No. 3,156,493, issued to Griffiths, U.S. Pat. No. 4,702,506, issued to Iimura, and U.S. Pat. No. 5,217,262, issued to Kurosaki, which are incorporated by reference as if fully set forth herein, describes touch latch mechanisms that have retractable arms. When a touch latch with a retractable arm is in an open position, pushing the arm may cause the arm to retract within the body of the latch. The movement of the arm may cause a tracing member to follow a path from a first stable position to a second stable position. Pushing the latch a second time may cause the tracing arm to travel the path from the second stable position to the first stable position so that the arm extends from the body of the touch latch.
In another type of touch latch, an arm of the latch is flexible. One end of the arm may be fixed in a set position. The tracing member may be located at an opposite end of the arm. The path that the tracing member follows may be located on a movable member. Closing the movable member against the arm causes the tracing member to follow the path so that the tracing member is located at a stable position of the path when the movable member is in a closed position. The tracing member holds the movable member in the closed position. Pushing the movable member a second time causes the tracing member to move away from the stable position so that the movable member is released. U.S. Pat. No. 4,657,292, issued to Bruck describes a touch latch mechanism having a flexible, fixed position arm.
Touch latches may be used to hold a closure member in a closed position. In some applications, such as in aircraft applications and marine applications, the touch latch may have to resist large forces exerted against the touch latch by shifting contents within the closure. Many currently available touch latches are not able to withstand large forces exerted against the touch latch without releasing the closure member. Large forces exerted against the touch latch may also damage or destroy a touch latch.
Sometimes a user of a touch latch may try to improperly open a storage compartment that is latched with a touch latch. For example, a user may pull outwardly upon the door of a storage compartment, instead of pushing the door inwards. Many currently available touch latches are not able to withstand outward pulling forces exerted against a touch latch without releasing the closure member and without damaging the touch latch.
The design of some touch latches may allow the touch latch to open if the spring that biases the arm away from the body of the touch latch breaks. It is desirable to have a touch latch that will remain in a closed position if the spring that guides the tracing member along should break during use.
The problems outlined above may in large part be solved by a latch system that may include a push-push latch and a catch. The push-push latch may be small in size, yet the push-push latch may have a large strength to size ratio. The push-push latch may include an arm that is rotationally attached to a body of the latch. An end of the arm may engage the catch when the push-push latch is in a closed position.
In an embodiment, the push-push latch may have a body with a groove formed in an inner surface of the body. A lever arm may be rotatively coupled to the body at a pivot connection. One arm of a torsion spring may contact the body of the latch. A second arm of the torsion spring may contact the lever arm. The force that the torsion spring applies to the push-push latch will tend to rotate the lever arm away from the body of the latch. One end of a toggle may be pivotally coupled to the lever arm between an end of the lever arm and the pivot connection. A second end of the toggle may have a tracing member that is positioned within the groove in the body of the latch. The groove may have two stable positions. When the tracing member is in the first stable position, the push-push latch is in an open position. When the tracing member is in the second stable position, the push-push latch is in a closed position. When the push-push latch is in the closed position, an end of the lever arm may be held by the catch of the latch system.
When the lever arm is rotated away from the body as far as the toggle arm will allow, the tracing member is in the first position, and the lever arm is in an open position. When the lever arm is rotated toward the body by a closing force, the tracing member follows the path of the groove towards the second position. If the closing force is not large enough to move the tracing member from the first stable position to the second stable position, the torsion spring will tend to force the lever arm away from the body to return the lever arm to the open position when the closing force is removed. If the closing force is large enough to move the tracing member from the first stable position to the second stable position, the tracing member will move to the second stable position when the closing force is removed from the lever arm. When the tracing member is in the second stable position, the lever arm is in a closed position. An end of the lever arm may be held by the catch when the lever arm is in the closed position. The end of the lever arm may be a roller that is rotationally connected to the lever arm.
When the lever arm is in the closed position, applying an opening force to the lever arm that pushes the lever arm towards the body of the push-push latch may cause the tracing member to follow a path that moves the tracing member from the first stable position to the second stable position. If the opening force is not large enough to move the tracing member from the second stable position to the first stable position, the tracing member will return to the second stable position when the opening force is removed from the lever arm. The lever arm will remain in the closed position, and the end of the lever arm will not be released from the catch. If the opening force is large enough to move the tracing member from the second stable position to the first stable position, the tracing member will move to the first stable position when the opening force is removed. The end of the lever arm will be released from the catch, and the lever arm will move to the open position.
Advantages of the push-push latch include that the latch may be small, light weight, and strong. The small size of the push-push latch may allow the latch to be coupled to space restricted surfaces and confined regions that were not previously usable for latching mechanisms. The small size, light weight and high strength characteristics of the push-push latch may make the push-push latch ideal for use in space, aircraft, and marine applications. The push-push latch may be able to withstand large forces that attempt to improperly open the latch without breaking the latch, and without opening the latch. Forces that try to improperly open the push-push latch may result in the application of tension to the toggle of the latch. The toggle, the connection between the toggle and the body, and the connection between the toggle and the lever arm may be made of materials that have good resistance to failure due to tension applied through the toggle. A push-push latch that is less than 1xe2x85x9xe2x80x3xc3x97xc2xexe2x80x3xc3x97xe2x85x9cxe2x80x3 when in a closed position (less than 1xc2xdxe2x80x3xc3x97xc2xexe2x80x3xc3x97xe2x85x9cxe2x80x3 when in an open position) may withstand outward pulling force in excess of 90 pounds of force without releasing the push-push latch from the closed position and without damaging the latch. Changing the materials and/or size of a push-push latch may allow the push-push latch to withstand outward pulling force in excess of 150 pounds of force without releasing the push-push latch from a closed position and without damaging the latch.
Another advantage of the push-push latch is that the latch will not release if the torsion spring breaks while the latch is in a closed position. A push-push latch may be used in a system wherein items are stored within a closure, and a door of the closure may be held in a closed position by the latch. If the torsion spring of the push-push latch happens to break while the push-push latch is in a closed position, the latch will not release the door of the closure. The push-push latch will prevent the contents of the closure from discharging from the closure even if the torsion spring of the latch breaks. In other words, the push-push latch will still function even if the push-push latch should partially fail.
Another advantage of the push-push latch is that the latch may be formed of materials that are strong, hard, non-corrosive, and nonflammable. The moving parts of the push-push latch, and the parts of the latch that come into contact with the moving parts, may be made of materials that inhibit galling. The use of non-galling materials may allow the push-push latch to be operated without the need for lubrication of the moving parts of the latch and without excessive wear to the parts of the latch.
A further advantage of the push-push latch is that no visible hardware is present on exterior surfaces of a closure when the latch is used as a part of a latching system for the closure. Further advantages of the push-push latch are that the latch may be sturdy, durable, simple, efficient, and reliable; yet the latch may also be easy to manufacture, install, maintain and use.